MR arthrography including abduction and external rotation images in the assessment of atraumatic multidirectional instability of the shoulder

Objective

To evaluate diagnostic signs and measurements in the assessment of capsular redundancy in atraumatic multidirectional instability (MDI) of the shoulder on MR arthrography (MR-A) including abduction/external rotation (ABER) images.

Methods

Twenty-one MR-A including ABER position of 20 patients with clinically diagnosed MDI and 17 patients without instability were assessed by three radiologists. On ABER images, presence of a layer of contrast between the humeral head (HH) and the anteroinferior glenohumeral ligament (AIGHL) (crescent sign) and a triangular-shaped space between the HH, AIGHL and glenoid (triangle sign) were evaluated; centring of the HH was measured. Anterosuperior herniation of the rotator interval (RI) capsule and glenoid version were determined on standard imaging planes.

Results

The crescent sign had a sensitivity of 57 %/62 %/48 % (observers 1/2/3) and specificity of 100 %/100 %/94 % in the diagnosis of MDI. The triangle sign had a sensitivity of 48 %/57 %/48 % and specificity of 94 %/94 %/100 %. The combination of both signs had a sensitivity of 86 %/90 %/81 % and specificity of 94 %/94 %/94 %. A positive triangle sign was significantly associated with decentring of the HH. Measurements of RI herniation, RI width and glenoid were not significantly different between both groups.

Conclusions

Combined assessment of redundancy signs on ABER position MR-A allows for accurate differentiation between patients with atraumatic MDI and patients with clinically stable shoulders; measurements on standard imaging planes appear inappropriate.

Key Points

? MR arthrography has the possibility to accurately identify patients with atraumatic MDI. ? Imaging of the shoulder in abduction and external rotation provides additive information. ? Capsular enlargement of the shoulder can be diagnosed on MR arthrography.     

Advances in the understanding of anterior instability of the shoulder

Anterior instability involves a spectrum of disease ranging from the obvious acute first-time dislocation to the athlete presenting with shoulder pain and no history suggestive of instability. It is important to recognize the pathophysiology and how it relates to this spectrum of disease. The arthroscope has helped to identify the underlying pathology in both acute and chronic situations. Diagnostically, a history of a painful shoulder, especially in the athlete, should suggest anterior instability. Tests of translation, apprehension, and the use of local anesthetic can be useful. Arthroscopy is used in situations in which the diagnosis is unclear. The management of anterior instability should emphasize strengthening of the rotator cuff and scapular stabilizers. Surgical repair requires correction of the underlying pathology with minimization of damage to other structures. Arthroscopic management of anterior instability includes repair, debridement of intra-articular lesions, and the possibility of acute correction of the pathoanatomic lesions.     

Diagnosis and management of traumatic and atraumatic hip instability in the athletic patient

Although relatively uncommon compared with the shoulder, hip instability can be a source of significant disability and is a commonly unrecognized injury. Hip instability can be traumatic or atraumatic in origin. Our understanding and treatment plan for hip instability due to traumatic events is well established. However, our understanding and treatment modalities for hip instability due to atraumatic events or repetitive motion in high level athletes are not as well defined. In this article, we will review the spectrum of traumatic and atraumatic hip instability and discuss the relevant anatomy, history, and physical examination findings, imaging studies, and treatment options with a focus on hip arthroscopy, and review of the literature.     

Laser capsulorrhaphy for multidirectional instability of the shoulder

Multidirectional glenohumeral instability secondary to ligamentous laxity, capsular redundancy, and excessive joint volume occurs frequently. Traditional treatment programs have included conservative care, physical therapy, open surgical stabilization, and arthroscopic techniques. The laser-assisted capsular shift procedure uses low-dose, subablative laser energy to cause shrinkage of the shoulder capsule. The shrinkage of the shoulder capsule results in a decrease in glenohumeral volume improving glenohumeral stability. The Holmium:YAG laser appears to be a useful instrument for the arthroscopic treatment of glenohumeral instability. Holmium:YAG laser energy can be used to thermally modify capsular tissue to cause a reduction in its length without detrimental effects to the viscoelastic properties of the tissue. Early clinical reports have been promising and further follow-up is required to assess the long-term outcome of this procedure.     

Arthroscopic capsulolabroplasty for posteroinferior multidirectional instability of the shoulder

BACKGROUND: Arthroscopic treatment of posteroinferior multidirectional instability of the shoulder is not well documented. PURPOSE: To evaluate pathologic lesions of posteroinferior multidirectional instability and the results of arthroscopic capsulolabroplasty. STUDY DESIGN: Prospective nonrandomized clinical trial. METHODS: Thirty-one patients with posteroinferior multidirectional instability were prospectively evaluated after arthroscopic capsulolabroplasty (mean follow-up, 51 months). Labral lesion and height were measured in the MRI arthrogram and arthroscopic examination. RESULTS: All patients had a labral lesion and variable capsular stretching in the posteroinferior aspect. There were 11 type I labral lesions (incomplete detachment), 12 type II (the Kim's lesion: incomplete and concealed avulsion), 6 type III (chondrolabral erosion), and 2 type IV (flap tear). All patients with type II and III lesions had chondrolabral retroversion, with lost labral height in the MRI arthrogram and arthroscopic examination. Twenty-one patients had an excellent Rowe score, nine had good scores, and one had a fair score. Thirty patients had stable shoulders, and one had recurrent instability. All patients had improved shoulder scores and function and pain scores. CONCLUSIONS: Symptomatic patients with posteroinferior multidirectional instability had posteroinferior labral lesions, including retroversion of the posteroinferior labrum, which were previously unrecognized. Restoration of the labral buttress and capsular tension by arthroscopic capsulolabroplasty successfully stabilized shoulders with posteroinferior multidirectional instability.     

Arthroscopic versus open Bankart repair for traumatic anterior shoulder instability

After more than 15 years of experience, arthroscopic shoulder stabilization is becoming less controversial. Historically, recurrence rates following arthroscopic stabilization have been higher than with open stabilization. Although a negligible advantage may exist in terms of expedited postoperative rehabilitation and improved postoperative recovery of motion, critics suggest that its use in contact athletes be limited. The indications for arthroscopic stabilization are expanding, in part, because of improved understanding of the pathophysiology of shoulder instability. Understanding the mechanism of recurrent instability following arthroscopic stabilization offers clues to how physicians can prevent unsatisfactory results in the future. With newer instrumentation and the ability to thermally treat capsular tissue, coexisting pathology, such as capsular plastic deformation, rotator interval lesions, and unrecognized intra-articular pathology, can now be addressed arthroscopically. The judicious use of these techniques is warranted until long-term study results become available. Ideal patients for arthroscopic Bankart repair have a discrete Bankart lesion; a robust, well-developed IGHL; no significant capsular laxity or intraligamentous injury; and an absence of concomitant intra-articular pathology. Additional findings on MR imaging or CT evidence of a discrete labral lesion and pure unidirectional anterior instability during EUA are also good prognostic indicators for arthroscopic Bankart repair. Arthroscopic criteria that render patients less appropriate for an arthroscopic repair include capsular injury, capsular laxity, a bony Bankart lesion, glenohumeral arthritis, and a rotator cuff tear. The authors' believe that either absent or patulous, poorly developed glenohumeral ligaments represent a poor prognostic indicator for a successful outcome following standard arthroscopic Bankart repair. Individuals with poor-quality tissue are more predictably managed using open capsulorrhaphy. Patients with pathologic ligamentous laxity in the absence of a Bankart lesion or any apparent intraligamentous injury to the IGHL are also good candidates for treatment with an open capsulorrhaphy. Findings determined from a thorough physical examination, EUA, and the pathology appreciated during diagnostic arthroscopy help to appropriately choose the surgical procedure that effectively addresses pathology in patients who present with recurrent traumatic anterior instability. Patient preferences and surgical experience are important determinants of procedure selection, and current arthroscopic techniques lack the versatility to uniformly address the entire spectrum of pathology that may be associated with traumatic anterior shoulder instability. Surgeons should always be prepared to convert to an open-stabilization technique if the arthroscopic technique is deficient in addressing all pathology identified at the time of surgery.     

Hip instability: anatomic and clinical considerations of traumatic and atraumatic instability

Hip instability is uncommon because of the substantial conformity of the osseous femoral head and acetabulum. It can be defined as extraphysiologic hip motion that causes pain with or without the symptom of hip joint unsteadiness. The cause can be traumatic or atraumatic, and is related to?both bony and soft tissue abnormality. Gross instability caused by trauma or iatrogenic injury has been shown to improve with surgical correction of the underlying deficiency. Subtle microinstability, particularly from microtraumatic or atraumatic causes, is an evolving concept with early surgical treatment results that are promising.     

Nonoperative management for in-season athletes with anterior shoulder instability

BACKGROUND: Acute or recurrent anterior shoulder instability is a frequent injury for in-season athletes. Treatment options for this injury include shoulder immobilization, rehabilitation, and shoulder stabilization surgery. PURPOSE: To determine if in-season athletes can be returned to their sports quickly and effectively after nonoperative treatment for an anterior instability episode. METHODS: Over a 2-year period, 30 athletes matched the inclusion criteria for this study. Nineteen athletes had experienced anterior dislocations, and 11 had experienced subluxations. All were treated with physical therapy and fitted, if appropriate, with a brace. These athletes were followed for the number of recurrent instability episodes, additional injuries, subjective ability to compete, and ability to complete their season or seasons of choice. RESULTS: Twenty-six of 30 athletes were able to return to their sports for the complete season at an average time missed of 10.2 days (range, 0-30 years). Ten athletes suffered sport-related recurrent instability episodes (range, 0-8 years). An average of 1.4 recurrent instability episodes per season per athlete occurred. There were no further injuries attributable to the shoulder instability. Sixteen athletes underwent surgical stabilization for their shoulders during the subsequent off-season. CONCLUSIONS: Most of the athletes were able to return to their sport and complete their seasons after an episode of anterior shoulder instability, although 37% experienced at least 1 additional episode of instability during the season.     

Relevance of arm position and muscle activity on three-dimensional glenohumeral translation in patients with traumatic and atraumatic shoulder instability

BACKGROUND: No quantitative data on glenohumeral translation exist allowing one to distinguish insufficiency of the active or passive stabilizers in different forms of shoulder instability. HYPOTHESIS: To determine whether 1) in traumatic or atraumatic shoulder instability an increase of glenohumeral translation can be observed in specific relevant arm positions, 2) muscle activity leads to recentering of the humeral head, and 3) there exist differences between traumatic and atraumatic instability. STUDY DESIGN: Prospective clinical trial. METHODS: In 12 patients with traumatic and 10 patients with atraumatic instability, both shoulders were examined in different arm positions-with and without muscle activity-by using open magnetic resonance imaging and a three-dimensional postprocessing technique. RESULTS: At 90 degrees of abduction and external rotation, translation (anterior-inferior) was significantly higher in patients with traumatic unstable shoulders compared with their contralateral side (3.6 +/- 1.5 versus 0.7 +/- 1.6 mm). In patients with atraumatic instability, significantly increased translation (4.7 +/- 2.0 mm) was observed, with the direction being nonuniform. Muscle activity led to significant recentering in traumatic but not in atraumatic instability. CONCLUSIONS: In traumatic instability, increased translation was observed only in functionally important arm positions, whereas intact active stabilizers demonstrate sufficient recentering. In atraumatic instability, a decentralized head position was recorded also during muscle activity, suggesting alterations of the active stabilizers. CLINICAL RELEVANCE: These data are relevant for optimizing diagnostics and therapeutic strategies.     

A modified capsular shift for atraumatic anterior-inferior shoulder instability

PURPOSE: To evaluate the long-term outcome of a modified inferior capsular shift procedure in patients with atraumatic anterior-inferior shoulder instability by analyzing a consecutive series of patients who had undergone a modified inferior capsular shift for this specific type of shoulder instability. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Between 1992 and 1997, 38 shoulders of 35 patients with atraumatic anterior-inferior shoulder instability that were unresponsive to nonoperative management were operated on using a modified capsular shift procedure with longitudinal incision of the capsule medially and a bony fixation of the inferior flap to the glenoid and labrum in the 1 o'clock to 3 o'clock position. The patient study group consisted of 9 men and 26 women with a mean age of 25.4 years (range, 15-55 years) at the time of surgery. The mean follow-up was 7.4 years (range, 4.0-11.4 years); 1 patient was lost to follow-up directly after surgery. The study group was evaluated according to the Rowe score. RESULTS: After 7.4 years, 2 patients experienced a single redislocation or resubluxation, 1 patient had recurrent dislocations, and 1 patient had a positive apprehension sign, which is an overall redislocation rate of 10.5%. The average Rowe score increased to 90.6 (SD = 19.7) points from 36.2 (SD = 13.5) points before surgery. Seventy-two percent of the patients participating in sports returned to their preoperative level of competition. CONCLUSIONS: Results in this series demonstrate the efficacy and durability of a modified capsular shift procedure for the treatment of atraumatic anterior-inferior shoulder instability.     

Arthroscopic bankart repair with the suretac device for traumatic anterior shoulder instability in athletes

Arthroscopic treatment of anterior shoulder instability in the athlete has evolved tremendously over the past decade. Currently, most techniques include the use of suture and suture anchors. However, the variety of arthroscopic instruments and techniques that are available shows the complexity of intra-articular tissue fixation, which includes anchor placement, suture passing, and knot tying. Stabilization using the Suretac device (Acufex Microsurgical, Mansfield, MA) simplifies tissue fixation by eliminating the need for arthroscopic suture passing and intraarticular knot tying. However, a successful outcome is highly dependent on accurate patient selection. Preoperative evaluation, examination under anesthesia, and the pathoanatomy defined by a thorough arthroscopic examination suggest the most effective treatment strategy. The ideal candidate for shoulder stabilization using the Suretac device is an athlete with a relatively pure traumatic anterior instability pattern with detachment pathology (eg, a Bankart lesion) and minimal capsular deformation.     

Arthroscopic management of anterior shoulder instability with glenoid bone defects

Bony deficiency of the anterior glenoid rim may significantly contribute to recurrent shoulder instability. Today, based on clinical and biomechanical data, a bony reconstruction is recommended in patients with bone loss of greater than 20–25 % of the glenoid surface area. Recent advances in arthroscopic instruments and techniques presently allow minimally invasive and arthroscopic reconstruction of glenoid bone defects and osteosynthesis of glenoid fractures. This article underlines the role of glenoid bone deficiency in recurrent shoulder instability, provides an update on the current management regarding this pathology and highlights the modern techniques for surgical treatment. Therefore, it can help orthopaedic surgeons in the treatment and decision-making when dealing with these difficult to treat patients in daily clinical practice. Level of evidence V.     

Traumatic anterior shoulder instability in the athlete

Anterior glenohumeral dislocation is common among athletes and may progress to recurrent instability. The pathoanatomy of instability and specific needs of each individual should be considered to prevent unnecessary absence from sport. Traditionally, primary dislocations have been managed with immobilization followed by rehabilitation exercises and a return to sporting activity. However, arthroscopic stabilization and external rotation bracing are increasingly used to prevent recurrent instability. In addition to the typical capsulolabral disruptions seen following a primary dislocation, patients with recurrent instability often have coexistent osseous injury to the humeral head and glenoid. In patients without significant bone loss, open soft‐tissue stabilizations have long been considered the ‘gold standard treatment’ for recurrent instability, but with advances in technology, arthroscopic procedures have gained popularity. However, enthusiasm for arthroscopic repair has not been supported with evidence, and there is currently no consensus for treatment. In patients with greater bone loss, soft‐tissue stabilization alone is insufficient to treat recurrent instability and open repair or bone augmentation should be considered. We explore the recent advances in epidemiology, classification, pathoanatomy and clinical assessment of young athletes with anterior shoulder instability, and compare the relative merits and outcomes of the different forms of treatment.     

Arthroscopic laser-assisted capsular shift in the treatment of patients with multidirectional shoulder instability

BACKGROUND: In recent years, various investigators have begun using lasers in the treatment of shoulder instability. HYPOTHESIS: Arthroscopic laser-assisted capsular shift is an effective treatment for patients with multidirectional shoulder instability. STUDY DESIGN: Retrospective cohort study. METHODS: We retrospectively identified 28 patients (30 shoulders) with multidirectional shoulder instability who were unresponsive to nonoperative management and who had undergone the laser-assisted capsular shift procedure. Twenty-five patients (27 shoulders) with an average follow-up of 28 months were available for review. All patients underwent a physical examination and completed a general questionnaire; the University of California, Los Angeles, shoulder rating scale; the Western Ontario Shoulder Instability Index; and the Short-Form 36 quality of life index. RESULTS: In 22 shoulders, results of the procedure were considered a success because the patients had no recurrent symptoms and at latest follow-up had required no further operative intervention. In five shoulders, results were considered a failure because of recurrent pain or instability and the need for an open capsular shift procedure. With recurrent instability as a measure of failure, the overall success rate was 81.5%. CONCLUSIONS: Our results with laser-assisted capsular shift are comparable with the results of other open and arthroscopic techniques in relieving pain and returning athletes to their premorbid function.     

Kinematic and muscle activity characteristics of multidirectional shoulder joint instability during elevation

Alterations of shoulder motion have been suggested to be associated with shoulder disorders. The objective of this study was to perform a 3D motion analysis (kinematic and electromyographical) of skeletal elements and muscles of shoulder joint in patients with multidirectional instability. Fifteen patients with multidirectional instability and 15 normal controls were investigated during continuous elevation in the scapular plane. The spatial coordinates of 16 anatomical points of the shoulder to determine kinematical parameters were quantified by an ultrasound-based motion analyzer. The activities of 12 muscles were measured by surface electromyography. Kinematic characteristics of motion were identified by scapulothoracic, glenohumeral, and humeral elevation angles; range of angles; scapulothoracic and glenohumeral rhythm; scapulothoracis, glenohumeral, and scapuloglenoid ratios; and the relative displacement between the rotation centers of the humerus and the scapula. The electromyographical characteristics of motion were modeled by the on–off pattern of muscle activity. Significant alterations in kinematical parameters were observed between patients and asymptomatic volunteers. The anterior, posterior, and inferior dislocations of shoulders with multidirectional instability could be properly modeled by the relative displacement between the rotation centers of the scapula and humerus. The shorter activity by m. pectoralis maior and all three parts of m. deltoideus and longer activity by m. supraspinatus, m. biceps brachii, and m. infraspinatus assure the centralization of the glenuhumeral head of a shoulder with multidirectional instability.     

Posterior glenoid rim deficiency in recurrent (atraumatic) posterior shoulder instability

Objective. To assess the shape of the posterior glenoid rim in patients with recurrent (atraumatic) posterior instability. Design and patients.CT examinations of 15 shoulders with recurrent (atraumatic) posterior instability were reviewed in masked fashion with regard to abnormalities of the glenoid shape, specifically of its posterior rim. The glenoid version was also assessed. The findings were compared with the findings in 15 shoulders with recurrent anterior shoulder instability and 15 shoulders without instability. For all patients, surgical correlation was available. Results.Fourteen of the 15 (93%) shoulders with recurrent (atraumatic) posterior shoulder instability had a deficiency of the posteroinferior glenoid rim. In patients with recurrent anterior instability or stable shoulders such deficiencies were less common (60% and 73%, respectively). The craniocaudal length of the deficiencies was largest in patients with posterior instability. When a posteroinferior deficiency with a craniocaudal length of 12 mm or more was defined as abnormal, sensitivity and specificity for diagnosing recurrent (atraumatic) posterior instability were 86.7% and 83.3%, respectively. There was a statistically significant difference in glenoid version between shoulders with posterior instability and stable shoulders (P=0.01). Conclusion.Recurrent (atraumatic) posterior shoulder instability should be considered in patients with a bony deficiency of the posteroinferior glenoid rim with a craniocaudal length of more than 12 mm. Received: 13 September 1999 Revision requested: 9 November 1999 Revision received: 13 December 1999 Accepted: 4 January 2000     

Arthroscopic reconstructionof traumatic anterior instability

As techniques evolve, instrumentation improves, knowledge of instability increases, and as longer follow-upsbecome available, there appears to be a trend toward performing arthroscopic reconstruction for traumatic instability of the shoulder in athletes. It is essential to make an accurate diagnosis from an extensive history and a thorough physical examination. Surgically, all pathologic lesions should be identified and addressed. Specific care must be taken to protect the capsulolabral complex and prepare the glenoid to stimulate a healing response. The capsule must be freed and advanced superiorly and laterally to have a successful result. Although capsular injury and microscopic failure may not be apparent, it must be recognized and addressed. The depth of the glenohumeral cup must be restored and the anterior bumper re-created. Portal placement is critical in anchor insertion and knot typing. Arthroscopic reconstruction is only as successful as the healing that occurs. Athletes involved in contact sports and immature athletes are at high risk for recurrence of injury. Patients with large Hills-Sachs lesions and glenoid rim fractures are also at increased risk. To achieve successful results, the surgeon must pay strict attention to detail, technique, and patient selection. Arthroscopic reconstruction for traumatic instability in athletes is demanding but rewarding. Each athlete should be carefully evaluated for pathology, and functional demands, and expectations and treatment should be individualized.